US3596536A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transmission shift control with conditional automatic neutralizing means
Assignee: Caterpillar Inc
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Filing: 1969-10-24
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Granted: 1971-08-03
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Expires: 1989-10-24
Abstract
Abstract A compact simplified safety valve functions to inactivate fluid operated drive conditioning clutches of a vehicle transmission if the operating fluid pressure has remained below a particular level for a predetermined time and the control lever is not at the neutral position. This prevents the transmitting of drive through the transmission if the vehicle engine should be started up while the transmission controls are at a setting other than neutral.
Inventors
- 👤 James G Starling
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:05
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/18; F16H59/00; F16H59/68; F16H2059/6823; F16H59/74; F16H2059/746; F16H61/02; F16H61/0262; F16H61/0265; F16H61/0267; F16H61/0269
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
285 words
In combination with a transmission having a plurality of fluid pressure actuated drive conditioning devices including a first group of drive conditioning devices and second group of drive conditioning devices and wherein application of fluid pressure to at least one device of each group establishes a selected one of a plurality of drive conditions through the transmission, a control system comprising: a source of fluid under pressure, a first selector valve having a fluid inlet communicated with said source and having a plurality of drive positions for directing fluid to predetermined ones of said first group of devices and having a neutral position, said first selector valve having a fluid outlet which is communicated with said inlet at any of said drive positions and which is isolated from said inlet at said neutral position, a second selector valve having an inlet communicated with said outlet of said first selector valve and having a plurality of positions for directing fluid to predetermined ones of said second group of devices, and safety valve means having a first position at which the flow path from said source to said first selector valve is constricted and said outlet of said first selector valve is opened to drain and having a second position at which said flow path is enlarged and said outlet is isolated from said drain, said safety valve being biased towards said first position thereof and having means utilizing the pressure of fluid in said constricted flow path to overcome said bias and shift said safety valve to said second position thereof when said pressure rises and said first selector valve is at said neutral position thereby blocking relief of said rising pressure through said outlet thereof.
Claim 2
Dependent Claim
285 words
In combination with a transmission having a plurality of fluid pressure actuated drive conditioning devices including a first group of drive conditioning devices and second group of drive conditioning devices and wherein application of fluid pressure to at least one device of each group establishes a selected one of a plurality of drive conditions through the transmission, a control system comprising: a source of fluid under pressure, a first selector valve having a fluid inlet communicated with said source and having a plurality of drive positions for directing fluid to predetermined ones of said first group of devices and having a neutral position, said first selector valve having a fluid outlet which is communicated with said inlet at any of said drive positions and which is isolated from said inlet at said neutral position, a second selector valve having an inlet communicated with said outlet of said first selector valve and having a plurality of positions for directing fluid to predetermined ones of said second group of devices, and safety valve means having a first position at which the flow path from said source to said first selector valve is constricted and said outlet of said first selector valve is opened to drain and having a second position at which said flow path is enlarged and said outlet is isolated from said drain, said safety valve being biased towards said first position thereof and having means utilizing the pressure of fluid in said constricted flow path to overcome said bias and shift said safety valve to said second position thereof when said pressure rises and said first selector valve is at said neutral position thereby blocking relief of said rising pressure through said outlet thereof.
Claim 3
Dependent Claim
110 words
The combination defined in claim 1 wherein said safety valve means comprises a housing having a bore therein with a first portion of said bore forming a portion of the flow path from said source to said first selector valve and with a second portion of said bore forming a portion of the flow path between said outlet and said drain, and a spool movable axially in said bore and having a first edge which closes said first bore portion and a second edge which opens said second bore portion when said safety valve means is at said first position thereof, said first edge being bypassed by a flow constriction.
Claim 4
Dependent Claim
31 words
The combination defined in claim 2 wherein said flow constriction is situated in said spool and communicates said passage with said source at all positions of said spool in said bore.
Claim 5
Dependent Claim
49 words
The combination defined in claim 1 further comprising a first pressure modulating valve disposed in said flow path between said safety valve means and said first selector valve, aNd a second pressure modulating valve disposed in the flow path between said first selector valve and said second selector valve.
Claim 6
Dependent Claim
59 words
The combination defined in claim 2 wherein said spool is biased towards said first position by spring means acting thereon and wherein said spool has an axial passage communicating the region between said first edge and said first selector valve inlet with the region adjacent an end of said spool to utilize said fluid pressure to overcome said bias.
Claim 7
Dependent Claim
50 words
The combination defined in claim 5 wherein said axial passage in said spool contains a flow constriction whereby fluid pressure in said region adjacent an end of said spool is maintained in the presence of brief pressure drops within said region between said first edge and said first selector valve.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-02 | 1975-02-01 | 1975-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-02 | 1979-02-01 | 1979-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-02 | 1983-02-01 | 1983-08-03 | $7700.00 | Window Closed / Lapsed |